This invention relates to an apparel fiber of nylon containing 5 to 15 % by weight poly(N,N-dimethylacrylamide) useful for improved comfort for wearers of apparel fabric made therefrom.
Consumers have long perceived cotton as one of the most comfortable apparel fibers, and have credited this perception largely to its moisture regain. Since the invention of nylon, researchers have sought techniques which confer to nylon an equivalent sense of comfort, and have centered this effort on increasing its moisture regain. In Japanese Publication No. 73-13 337 an N,N-dimethylacrylamide-methyl acrylate copolymer was added to polyamide spinning compositions to increase the hygroscopicity of the filaments. Also, a methyl acrylate-N,N-dimethylacrylamide copolymer was used for the same purpose in Japanese Publication No. 72-42 134. It is also known in Japanese Publication No. 72-41 744 to use poly(N,N-dimethylacrylamide) to increase the melt viscosity of polyamide. In Japanese Publication No. 77-25 895, N,N-dimethylacrylamide was grafted onto a polyester or similar polymer by radiation in the presence of a catalyst and in Japanese Publication No. 71-16893-R the graft copolymer of polyamide was an acrylamide and was taught to improve hygroscopic properties. U.S. Pat. No. 4 135 877 teaches the grafting onto a polyamide fiber of N,N'-methylenebis-acrylamide in the presence of an acid to improve hygroscopic properties. A similar teaching was found in U.S. Pat. No. 4,238,193 and a general teaching along the same lines is found in G.B. No. 1 355 846. Acrylamides are grafted onto a hollow fiber in Japanese Publication No. 55057-071.
Poly(N,N-dimethylacrylamide), hereinafter PDMAA, is prepared from a commercially available monomer and polymerizes readily using free radical initiators. The polymer is also available commercially.